1. Field of the Invention
The present invention relates to the field of medical devices and, in particular, to devices for delivery of medicament(s). More particularly, the present invention relates to a drug delivery device for delivery of insulin or other medicament(s), and methods therefor.
2. Description of the Related Art
Diabetes is a disease caused by the body's failure to produce adequate insulin or the cell's failure to respond to insulin resulting in high levels of sugar in the blood. If left untreated, diabetes can cause numerous complications. Typically, treatment for diabetes required both repeated checking of blood glucose levels and several injections of insulin throughout the day. Major drawbacks of such treatment were the need to draw blood and test glucose levels throughout the day, improper or low dosage amounts of insulin, contamination of the insulin delivery system, or lifestyle restriction. Low dosages of insulin over an extended period may cause heart disease, stroke, kidney failure, hypertension, or retinal damage.
Diabetes may be controlled by insulin replacement therapy in which insulin is delivered to the diabetic person, usually by injection, to counteract elevated blood glucose levels. Injectable insulin may be problematic due to the presence of air bubbles in a syringe, possibility of needle contamination, pain and infection. Recent therapies include the basal/bolus method of treatment in which basal, a long acting insulin medication, for example, Humalog® and Apidra®, is delivered via injection once every day. The basal provides the body with a relatively constant dose of insulin throughout the day. At mealtime, an additional dose of insulin, or bolus, is administered based on the amount of carbohydrate and protein in the meal. Accurate calculations of various parameters including the amount of carbohydrates and proteins consumed, and the lapse in time since the last dosage are necessary to determine the appropriate dosage of insulin. The dosages are thus prone to human error and the method is ineffective when doses are skipped, forgotten or miscalculated. Exercise, stress and other factors can also cause the calculations to be inaccurate.
To address these problems, programmable insulin delivery devices or insulin pumps were developed which seek to mimic the way a normal, healthy pancreas delivers insulin to the body. Insulin pumps are programmed to deliver a continual basal dose of insulin and occasionally a bolus dose in response to a patient's meal intake and physical activities. Additionally, the number of times a patient is required to draw blood and test their glucose during the day is reduced, thus lessening the pain and inconvenience of this disease. Also, micro-doses of insulin that can be delivered by programmable insulin delivery devices are more easily tolerated and rapidly metabolized by the body and thus, more effective.
Conventional insulin pumps are worn on the body and are connected to a patient via a cannula that is inserted somewhere on the patient's abdomen. The insulin is delivered under the skin and is absorbed into the body through the subcutaneous fat layer. Insulin pumps in the past have been quite large, some requiring the use of a shoulder bag to transport. Over time, they have become smaller in size and most pumps today are roughly the size of a deck of cards. Currently available insulin pumps include Animas OneTouch® Ping®, Deltec Cozmo®, Disetronic Accu-Chek Spirit®, Insulet OmniPod, Medtronic Paradigm™, Sooil USA Diabecare®II, and Nipro Amigo®.
With the decreased size of the pump unit also comes a decreased size in the medication reservoir. This reduced reservoir size means more frequent refilling, greater potential for contamination of the reservoir, more frequent changes of the cannula and tubing, and greater expense overall in treating the condition. Sooil USA Diabecare®II, Medtronic Paradigm®, Deltec Cozmo®, and Disetronic Accu-Chek Spirit® all require manual filling of the reservoir. The present invention overcomes the disadvantages of the existing systems by utilizing 300 u dual reservoirs prefilled with medicaments, with an option to redesign or re-conform the reservoirs to accommodate larger volumes.
Recent medical data suggests that a combination of insulin and another medication, such as glucagon, infused at different times or simultaneously, leads to better results in patients. An advantage of the dual reservoirs of the present invention is that they can be manufactured to contain two dissimilar medicaments within the same cartridge, for instance, insulin in one reservoir and a different medicament in a second reservoir.
Another disadvantage of many existing devices is the relatively short battery life, from 2-4 weeks for the Animas OneTouch® Ping® to 8-10 weeks for the Sooil USA Diabecare®II. The present invention has a rechargeable battery life of two (2) years, far surpassing all currently available insulin pumps. Yet another disadvantage of many existing insulin pumps is the size of the basal increment dose. The present invention currently allows a basal increment dose in the range of 0 to 0.5 u (in increments of tenths or hundredths of the maximum value of the range) that allows for more flexibility in dosing.
Among the other advantages of the present invention over prior art is the increased memory storage capacity. The present invention can store 5000 past basal and bolus events as well as 5000 past glucose readings in an onboard non-volatile memory, substantially more than existing insulin pumps including the Paradigm® Revel™. Storing more events is very helpful to physicians treating diabetic patients. Additionally, the present invention has a larger display screen than most other existing insulin pumps at 900 sq. mm. One advantage of a larger screen is that patients who may have impaired vision can easily read the display information on the screen.
Therefore, the need exists for a low-cost drug delivery device having a cartridge system containing a plurality of reservoirs, capable of working in tandem with a delivery pump system, for the delivery of more than one drug.